NOTE the classis American type out-of-round base. This seems to be caused from the unique removal process of the collapsible plungers. NOTE the oval shape of the bottom of the pin holes. NOTE the lip of glass on the narrow ends of the oval at the end of the pin hole. This looks like some of the glass was pulled out when the plunger expanded in the process of collapsing it for removal. This process was quirky and had some very interesting charachteristics as a result. Warped base, wierd threads, oval pin, inside vertical bar, dot at top of pin-hole.... Really Cool!